The art of inkjet printhead manufacturing is well known. In general, a printhead has a housing or body that defines an interior filled with one or more inks. A heater chip or other semiconductor die attaches to the body and resides in fluid communication with the one or more inks. A nozzle plate, attached to or formed with the heater chip, has a plurality of nozzle holes in communication with the heaters of the chip that serve, during use, to eject ink. After manufacture, and before use, however, the printhead must become packaged for shipping. Yet, during shipping, the printhead often experiences extreme environmental conditions, e.g., enormous temperature and pressure swings. Thereafter, it may remain packaged for a considerable length of time. Consequently, printhead packaging must contemplate reliability and durability.
With reference to FIG. 1, a printhead 10 with a nozzle plate 12 typically has a packaging tape 14 covering the individual nozzle holes 16 of the plate to prevent ink leakage during shipping and handling. Unfortunately, with reference to FIG. 2, the encapsulant beads 18 adjacent the nozzle plate regularly act as tent poles for the tape and, over time or immediately, cause the tape to lift off the nozzle plate in regions 20 and un-seal the nozzle holes 16. Eventually, this causes the printhead to leak.
To minimize this possibility, manufacturers have tried applying the encapsulant beads 18 as close as possible to their preferred placement position 24 (dashed line). In theory, this placement position extends from an edge 26 of the KAPTON of a TAB (tape automated bonded) circuit to an edge 28 of the nozzle plate and covers otherwise exposed portions of a lead beam 30 of the TAB circuit. Appreciating that tolerance stack-up issues abound in theoretically applying an encapsulant bead, and accurately placing a nozzle hole 16, producers of inkjet printheads often create large-as-necessary distances d1, d2 between the edge of the nozzle holes and the edge of the encapsulant bead to accommodate the tolerances. This, however, adversely limits a producer's ability to reduce the size of its heater chip 22 and attendant nozzle plate. While this did not, perhaps, create much of a problem in the past when heater chips tended to incorporate NMOS technology, as the future of heater chips appears to embrace CMOS technology, any prevention in reducing the size of the heater chip increases manufacturing costs, especially silicon costs.
Accordingly, the art of printhead manufacturing has a need for minimizing manufacturing costs, especially minimizing silicon-related expenses. Simultaneously, it also has need of creating and utilizing printhead packaging reliable throughout a variety of environmental conditions while durable for extended periods of time.